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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1861 Excerpt:...extent by means of proper arrangements. Experiment 1.--If a ray of light passes through a dense medium, it is, as it is called, "refracted,"--that is, the straight line of the ray is bent. Supposing, for instance, that you were looking at a fish in the water from the bank of a river: you would see the fish several inches from his real place, owing to the refraction of the rays of light passing from his body. We may here name one effect of refraction. On looking into a pond from its banks, the water appears of a depth one-third less than it really is; and in bathing you should allow for this, as you run the risk of a serious accident, by your making a mistake as to the real depth... Experiment 2.--Place in a basin a penny, and just retire so as to only see the extreme edge of the coin. Now get a friend to fill the basin with water, and the whole penny will become visible. Fig. 1 represents this, where the dotted lines show the real and apparent place of the coin. Fig. 1. a, the real place of the penny. b, its apparent position. Experiment 3.--A straight stick placed obliquely in a pail of water will, for the same reason, appear broken. It is owing to this refraction of light by our atmosphere that we obtain twilight; the colour of the clouds at the rising and setting of the sun; and that we also see the sun, as we think, some time before it really rises in the morning, owing to its rays passing into the air and being bent down, or refracted, to the eye. Fig. 2 gives an illustration of the appearance of the sun to a spectator before it has really risen. The inner circle is intended.Fig. 2. to represent the earth. The outer one the atmosphere. The upper line points to the sun's apparent position, and the lower one to its real place below the horizon....